#include "Mystdio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <assert.h>
#include <unistd.h>

#define FILE_MODE 0666


//"w", "a", "r"
_FILE* _fopen(const char* filename,const char* flag)
{
    assert(filename);
    assert(flag);
    int f = 0;
    int fd = 0;
    if(strcmp(flag,"w") == 0)
    {
        f = (O_CREAT|O_WRONLY|O_TRUNC);
        fd = open(filename,f,FILE_MODE);
    }
    else if(strcmp(flag,"a") == 0)
    {
        f = (O_CREAT|O_WRONLY|O_APPEND);
        fd = open(filename,f,FILE_MODE);
    }
    else if(strcmp(flag,"r") == 0)
    {
        f = O_RDWR;
        fd = open(filename,f);
    }
    else 
        return NULL;

    if(fd == -1) return NULL;

    _FILE* fp = (_FILE*)malloc(sizeof(_FILE));
    if(fp == NULL) return NULL;

    fp->fileno = fd;
    fp->flag = FLUSH_LINE;
    fp->out_pos = 0;

    return fp;
}

int _fwrite(_FILE* fp,const char* s,int len)
{
    memcpy(&fp->outbuffer[fp->out_pos],s,len);// 未作异常处理，也不考虑局部问题
    fp->out_pos += len;
    
    if(fp->flag&FLUSH_NOW)
    {
        write(fp->fileno,fp->outbuffer,fp->out_pos);
        fp->out_pos = 0;
    }
    else if(fp->flag&FLUSH_LINE)
    {
        if(fp->outbuffer[fp->out_pos-1] == '\n')// 不考虑其他情况
        {
            write(fp->fileno,fp->outbuffer,fp->out_pos);
            fp->out_pos = 0;
        }
    }
    else if(fp->fileno&FLUSH_ALL)
    {
        if(fp->out_pos == SIZE)
        {
            write(fp->fileno,fp->outbuffer,fp->out_pos);
            fp->out_pos = 0;
        }
    }

    return len;
}

void _fflush(_FILE* fp)
{
    if(fp->out_pos > 0)
    {
        write(fp->fileno,fp->outbuffer,fp->out_pos);
        fp->out_pos=0;
    }
}

void _fclose (_FILE* fp)
{
    if(fp == NULL) return;
    _fflush(fp);
    close(fp->fileno);
    free(fp);
}
